Concrete structures, subject to water pressure or buried, often include defects in tightness such as cracks, teeming arrests, non-waterproof expansion joints, coating defects of metal building components, porosities, honeycombing, at which water tightness is not ensured and where water leaks occur.
In order to ensure water tightness of these local defective areas, particularly when the liquid leaks are subject to pressure and/or have a high flow rate, it is not possible to use cement or concrete for sealing the leaking areas. The bulk concrete or cement setting time is too long to allow such leaks to be sealed.
In the case when despite everything a sealing-off of the leaks would be obtained with these materials, this seal would be rigid and would rapidly break subsequently to ground movements, expansions or contractions due to temperature differences.
It is known how to use two chemicals mixed before injection into the concrete by means of injectors, either screwed into the concrete at right angles to the defect, or of the expansive type.
These injectors have the following significant defects:
These injectors after drilling the concrete must be screwed into the support, and require the use of tools, their length and diameter should be different depending on the thickness of the concrete and on the nature of the problem to be solved.
If the injector is too short or positioned too close to the surface of the concrete, there is a high risk that the support is pulled off and/or burst upon applying pressure.
After drilling in the horizontal or vertical planes, it is required that the drilling dust be removed by blowing or washing, otherwise the injector will not be able to fulfil its role, the cracks or joints being filled with drilling dust.
After injection, the injectors are most often stuck by the injection product and cannot be recovered, they are then left in place or cut to be level with the surface of the support where they will oxidize, thereby causing oxidization spots which are difficult to suppress.
Quasi-routine replacement of these injectors has a significant effect on the financial supply and labor position.
The injector which has remained in place, blocked by the injection product, cannot be re-injected; a new perforation is required.
If the injectors have to be removed from the support with a tool of the “hub extractor” type, the operation is likely to cause damages at the surface of the support: the latter will have to be repaired.
The pistol connected to the injector should be connected and disconnected at each injection, which promotes flows of resin onto the surroundings, the tooling, the operator.
The injector-pistol assemblies on the market allow the contact of different components of the injected resin and require constant cleaning and attention, the chemicals being polymerized in the injector-pistol assemblies.
The injectors on the market have to be connected to an injection pistol, a mandatory relay towards the pump, thereby complicating the injection procedure, the maintenance, the reliability with an increase of costs.